i2c: mediatek: Add access to more than 8GB dram in i2c driver

Newer MTK chip support more than 8GB of dram. Replace support_33bits
with more general dma_max_support and remove mtk_i2c_set_4g_mode.

Reviewed-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
Signed-off-by: Qii Wang <qii.wang@mediatek.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>